1. Field of the Invention
The present invention relates to an improvement of a weft insertion apparatus for inserting a weft yarn on a measuring and storing device into a main nozzle.
2. Prior Art
Prior art automatic weft insertion apparatuses of this type have been disclosed in Japanese Patent Laid-Open Publication Nos. 64-40638, 62-62955, 61-119746 and the like. Inasmuch as the usual prior art weft insertion apparatus has a weft insertion suction tube positioned over a storage drum, an insert rapier is restricted in its operation for retaining and conveying a weft yarn extending between a winding yarn guide and the suction tube, whereby an erroneous operation is liable to occur. Furthermore, inasmuch as the insert rapier moves near the measuring and storing device and moves to an inlet of the main nozzle, the amount of motion in the radial direction of the storage drum and the insertion direction is increased whereby the likelihood of a mechanical error in increased which results in an unstable insertion operation.
It has been proposed that an intermediate nozzle be provided between the main nozzle and the measuring and storing device and the weft yarn be once inserted from the winding yarn guide to the intermediate nozzle and thereafter air be jetted from the intermediate nozzle toward the inlet of the main nozzle to complete the weft yarn insertion. In this case, inasmuch as the weft yarn is picked, in a weaving operation, through the intermediate nozzle, the picking operation is liable to be unstable due to the internal resistance of the intermediate nozzle, and the weft yarn insertion operation, i.e., inserting the weft yarn by air from the intermediate nozzle to the main nozzle becomes unstable. That is, air is rebounded at the inlet of the main nozzle and is liable to generate turbulence which requires a special arrangement of the main nozzle to avoid. However, in view of the picking operation, it is undesirable to provide the special arrangement of the main nozzle and such an arrangement is difficult.